xref: /linux/drivers/rtc/rtc-isl1208.c (revision fd639726bf15fca8ee1a00dce8e0096d0ad9bd18)
1 /*
2  * Intersil ISL1208 rtc class driver
3  *
4  * Copyright 2005,2006 Hebert Valerio Riedel <hvr@gnu.org>
5  *
6  *  This program is free software; you can redistribute  it and/or modify it
7  *  under  the terms of  the GNU General  Public License as published by the
8  *  Free Software Foundation;  either version 2 of the  License, or (at your
9  *  option) any later version.
10  *
11  */
12 
13 #include <linux/module.h>
14 #include <linux/i2c.h>
15 #include <linux/bcd.h>
16 #include <linux/rtc.h>
17 
18 /* Register map */
19 /* rtc section */
20 #define ISL1208_REG_SC  0x00
21 #define ISL1208_REG_MN  0x01
22 #define ISL1208_REG_HR  0x02
23 #define ISL1208_REG_HR_MIL     (1<<7)	/* 24h/12h mode */
24 #define ISL1208_REG_HR_PM      (1<<5)	/* PM/AM bit in 12h mode */
25 #define ISL1208_REG_DT  0x03
26 #define ISL1208_REG_MO  0x04
27 #define ISL1208_REG_YR  0x05
28 #define ISL1208_REG_DW  0x06
29 #define ISL1208_RTC_SECTION_LEN 7
30 
31 /* control/status section */
32 #define ISL1208_REG_SR  0x07
33 #define ISL1208_REG_SR_ARST    (1<<7)	/* auto reset */
34 #define ISL1208_REG_SR_XTOSCB  (1<<6)	/* crystal oscillator */
35 #define ISL1208_REG_SR_WRTC    (1<<4)	/* write rtc */
36 #define ISL1208_REG_SR_ALM     (1<<2)	/* alarm */
37 #define ISL1208_REG_SR_BAT     (1<<1)	/* battery */
38 #define ISL1208_REG_SR_RTCF    (1<<0)	/* rtc fail */
39 #define ISL1208_REG_INT 0x08
40 #define ISL1208_REG_INT_ALME   (1<<6)   /* alarm enable */
41 #define ISL1208_REG_INT_IM     (1<<7)   /* interrupt/alarm mode */
42 #define ISL1208_REG_09  0x09	/* reserved */
43 #define ISL1208_REG_ATR 0x0a
44 #define ISL1208_REG_DTR 0x0b
45 
46 /* alarm section */
47 #define ISL1208_REG_SCA 0x0c
48 #define ISL1208_REG_MNA 0x0d
49 #define ISL1208_REG_HRA 0x0e
50 #define ISL1208_REG_DTA 0x0f
51 #define ISL1208_REG_MOA 0x10
52 #define ISL1208_REG_DWA 0x11
53 #define ISL1208_ALARM_SECTION_LEN 6
54 
55 /* user section */
56 #define ISL1208_REG_USR1 0x12
57 #define ISL1208_REG_USR2 0x13
58 #define ISL1208_USR_SECTION_LEN 2
59 
60 static struct i2c_driver isl1208_driver;
61 
62 /* block read */
63 static int
64 isl1208_i2c_read_regs(struct i2c_client *client, u8 reg, u8 buf[],
65 		      unsigned len)
66 {
67 	u8 reg_addr[1] = { reg };
68 	struct i2c_msg msgs[2] = {
69 		{
70 			.addr = client->addr,
71 			.len = sizeof(reg_addr),
72 			.buf = reg_addr
73 		},
74 		{
75 			.addr = client->addr,
76 			.flags = I2C_M_RD,
77 			.len = len,
78 			.buf = buf
79 		}
80 	};
81 	int ret;
82 
83 	BUG_ON(reg > ISL1208_REG_USR2);
84 	BUG_ON(reg + len > ISL1208_REG_USR2 + 1);
85 
86 	ret = i2c_transfer(client->adapter, msgs, 2);
87 	if (ret > 0)
88 		ret = 0;
89 	return ret;
90 }
91 
92 /* block write */
93 static int
94 isl1208_i2c_set_regs(struct i2c_client *client, u8 reg, u8 const buf[],
95 		     unsigned len)
96 {
97 	u8 i2c_buf[ISL1208_REG_USR2 + 2];
98 	struct i2c_msg msgs[1] = {
99 		{
100 			.addr = client->addr,
101 			.len = len + 1,
102 			.buf = i2c_buf
103 		}
104 	};
105 	int ret;
106 
107 	BUG_ON(reg > ISL1208_REG_USR2);
108 	BUG_ON(reg + len > ISL1208_REG_USR2 + 1);
109 
110 	i2c_buf[0] = reg;
111 	memcpy(&i2c_buf[1], &buf[0], len);
112 
113 	ret = i2c_transfer(client->adapter, msgs, 1);
114 	if (ret > 0)
115 		ret = 0;
116 	return ret;
117 }
118 
119 /* simple check to see whether we have a isl1208 */
120 static int
121 isl1208_i2c_validate_client(struct i2c_client *client)
122 {
123 	u8 regs[ISL1208_RTC_SECTION_LEN] = { 0, };
124 	u8 zero_mask[ISL1208_RTC_SECTION_LEN] = {
125 		0x80, 0x80, 0x40, 0xc0, 0xe0, 0x00, 0xf8
126 	};
127 	int i;
128 	int ret;
129 
130 	ret = isl1208_i2c_read_regs(client, 0, regs, ISL1208_RTC_SECTION_LEN);
131 	if (ret < 0)
132 		return ret;
133 
134 	for (i = 0; i < ISL1208_RTC_SECTION_LEN; ++i) {
135 		if (regs[i] & zero_mask[i])	/* check if bits are cleared */
136 			return -ENODEV;
137 	}
138 
139 	return 0;
140 }
141 
142 static int
143 isl1208_i2c_get_sr(struct i2c_client *client)
144 {
145 	return i2c_smbus_read_byte_data(client, ISL1208_REG_SR);
146 }
147 
148 static int
149 isl1208_i2c_get_atr(struct i2c_client *client)
150 {
151 	int atr = i2c_smbus_read_byte_data(client, ISL1208_REG_ATR);
152 	if (atr < 0)
153 		return atr;
154 
155 	/* The 6bit value in the ATR register controls the load
156 	 * capacitance C_load * in steps of 0.25pF
157 	 *
158 	 * bit (1<<5) of the ATR register is inverted
159 	 *
160 	 * C_load(ATR=0x20) =  4.50pF
161 	 * C_load(ATR=0x00) = 12.50pF
162 	 * C_load(ATR=0x1f) = 20.25pF
163 	 *
164 	 */
165 
166 	atr &= 0x3f;		/* mask out lsb */
167 	atr ^= 1 << 5;		/* invert 6th bit */
168 	atr += 2 * 9;		/* add offset of 4.5pF; unit[atr] = 0.25pF */
169 
170 	return atr;
171 }
172 
173 static int
174 isl1208_i2c_get_dtr(struct i2c_client *client)
175 {
176 	int dtr = i2c_smbus_read_byte_data(client, ISL1208_REG_DTR);
177 	if (dtr < 0)
178 		return -EIO;
179 
180 	/* dtr encodes adjustments of {-60,-40,-20,0,20,40,60} ppm */
181 	dtr = ((dtr & 0x3) * 20) * (dtr & (1 << 2) ? -1 : 1);
182 
183 	return dtr;
184 }
185 
186 static int
187 isl1208_i2c_get_usr(struct i2c_client *client)
188 {
189 	u8 buf[ISL1208_USR_SECTION_LEN] = { 0, };
190 	int ret;
191 
192 	ret = isl1208_i2c_read_regs(client, ISL1208_REG_USR1, buf,
193 				    ISL1208_USR_SECTION_LEN);
194 	if (ret < 0)
195 		return ret;
196 
197 	return (buf[1] << 8) | buf[0];
198 }
199 
200 static int
201 isl1208_i2c_set_usr(struct i2c_client *client, u16 usr)
202 {
203 	u8 buf[ISL1208_USR_SECTION_LEN];
204 
205 	buf[0] = usr & 0xff;
206 	buf[1] = (usr >> 8) & 0xff;
207 
208 	return isl1208_i2c_set_regs(client, ISL1208_REG_USR1, buf,
209 				    ISL1208_USR_SECTION_LEN);
210 }
211 
212 static int
213 isl1208_rtc_toggle_alarm(struct i2c_client *client, int enable)
214 {
215 	int icr = i2c_smbus_read_byte_data(client, ISL1208_REG_INT);
216 
217 	if (icr < 0) {
218 		dev_err(&client->dev, "%s: reading INT failed\n", __func__);
219 		return icr;
220 	}
221 
222 	if (enable)
223 		icr |= ISL1208_REG_INT_ALME | ISL1208_REG_INT_IM;
224 	else
225 		icr &= ~(ISL1208_REG_INT_ALME | ISL1208_REG_INT_IM);
226 
227 	icr = i2c_smbus_write_byte_data(client, ISL1208_REG_INT, icr);
228 	if (icr < 0) {
229 		dev_err(&client->dev, "%s: writing INT failed\n", __func__);
230 		return icr;
231 	}
232 
233 	return 0;
234 }
235 
236 static int
237 isl1208_rtc_proc(struct device *dev, struct seq_file *seq)
238 {
239 	struct i2c_client *const client = to_i2c_client(dev);
240 	int sr, dtr, atr, usr;
241 
242 	sr = isl1208_i2c_get_sr(client);
243 	if (sr < 0) {
244 		dev_err(&client->dev, "%s: reading SR failed\n", __func__);
245 		return sr;
246 	}
247 
248 	seq_printf(seq, "status_reg\t:%s%s%s%s%s%s (0x%.2x)\n",
249 		   (sr & ISL1208_REG_SR_RTCF) ? " RTCF" : "",
250 		   (sr & ISL1208_REG_SR_BAT) ? " BAT" : "",
251 		   (sr & ISL1208_REG_SR_ALM) ? " ALM" : "",
252 		   (sr & ISL1208_REG_SR_WRTC) ? " WRTC" : "",
253 		   (sr & ISL1208_REG_SR_XTOSCB) ? " XTOSCB" : "",
254 		   (sr & ISL1208_REG_SR_ARST) ? " ARST" : "", sr);
255 
256 	seq_printf(seq, "batt_status\t: %s\n",
257 		   (sr & ISL1208_REG_SR_RTCF) ? "bad" : "okay");
258 
259 	dtr = isl1208_i2c_get_dtr(client);
260 	if (dtr >= 0 - 1)
261 		seq_printf(seq, "digital_trim\t: %d ppm\n", dtr);
262 
263 	atr = isl1208_i2c_get_atr(client);
264 	if (atr >= 0)
265 		seq_printf(seq, "analog_trim\t: %d.%.2d pF\n",
266 			   atr >> 2, (atr & 0x3) * 25);
267 
268 	usr = isl1208_i2c_get_usr(client);
269 	if (usr >= 0)
270 		seq_printf(seq, "user_data\t: 0x%.4x\n", usr);
271 
272 	return 0;
273 }
274 
275 static int
276 isl1208_i2c_read_time(struct i2c_client *client, struct rtc_time *tm)
277 {
278 	int sr;
279 	u8 regs[ISL1208_RTC_SECTION_LEN] = { 0, };
280 
281 	sr = isl1208_i2c_get_sr(client);
282 	if (sr < 0) {
283 		dev_err(&client->dev, "%s: reading SR failed\n", __func__);
284 		return -EIO;
285 	}
286 
287 	sr = isl1208_i2c_read_regs(client, 0, regs, ISL1208_RTC_SECTION_LEN);
288 	if (sr < 0) {
289 		dev_err(&client->dev, "%s: reading RTC section failed\n",
290 			__func__);
291 		return sr;
292 	}
293 
294 	tm->tm_sec = bcd2bin(regs[ISL1208_REG_SC]);
295 	tm->tm_min = bcd2bin(regs[ISL1208_REG_MN]);
296 
297 	/* HR field has a more complex interpretation */
298 	{
299 		const u8 _hr = regs[ISL1208_REG_HR];
300 		if (_hr & ISL1208_REG_HR_MIL)	/* 24h format */
301 			tm->tm_hour = bcd2bin(_hr & 0x3f);
302 		else {
303 			/* 12h format */
304 			tm->tm_hour = bcd2bin(_hr & 0x1f);
305 			if (_hr & ISL1208_REG_HR_PM)	/* PM flag set */
306 				tm->tm_hour += 12;
307 		}
308 	}
309 
310 	tm->tm_mday = bcd2bin(regs[ISL1208_REG_DT]);
311 	tm->tm_mon = bcd2bin(regs[ISL1208_REG_MO]) - 1;	/* rtc starts at 1 */
312 	tm->tm_year = bcd2bin(regs[ISL1208_REG_YR]) + 100;
313 	tm->tm_wday = bcd2bin(regs[ISL1208_REG_DW]);
314 
315 	return 0;
316 }
317 
318 static int
319 isl1208_i2c_read_alarm(struct i2c_client *client, struct rtc_wkalrm *alarm)
320 {
321 	struct rtc_time *const tm = &alarm->time;
322 	u8 regs[ISL1208_ALARM_SECTION_LEN] = { 0, };
323 	int icr, yr, sr = isl1208_i2c_get_sr(client);
324 
325 	if (sr < 0) {
326 		dev_err(&client->dev, "%s: reading SR failed\n", __func__);
327 		return sr;
328 	}
329 
330 	sr = isl1208_i2c_read_regs(client, ISL1208_REG_SCA, regs,
331 				   ISL1208_ALARM_SECTION_LEN);
332 	if (sr < 0) {
333 		dev_err(&client->dev, "%s: reading alarm section failed\n",
334 			__func__);
335 		return sr;
336 	}
337 
338 	/* MSB of each alarm register is an enable bit */
339 	tm->tm_sec = bcd2bin(regs[ISL1208_REG_SCA - ISL1208_REG_SCA] & 0x7f);
340 	tm->tm_min = bcd2bin(regs[ISL1208_REG_MNA - ISL1208_REG_SCA] & 0x7f);
341 	tm->tm_hour = bcd2bin(regs[ISL1208_REG_HRA - ISL1208_REG_SCA] & 0x3f);
342 	tm->tm_mday = bcd2bin(regs[ISL1208_REG_DTA - ISL1208_REG_SCA] & 0x3f);
343 	tm->tm_mon =
344 		bcd2bin(regs[ISL1208_REG_MOA - ISL1208_REG_SCA] & 0x1f) - 1;
345 	tm->tm_wday = bcd2bin(regs[ISL1208_REG_DWA - ISL1208_REG_SCA] & 0x03);
346 
347 	/* The alarm doesn't store the year so get it from the rtc section */
348 	yr = i2c_smbus_read_byte_data(client, ISL1208_REG_YR);
349 	if (yr < 0) {
350 		dev_err(&client->dev, "%s: reading RTC YR failed\n", __func__);
351 		return yr;
352 	}
353 	tm->tm_year = bcd2bin(yr) + 100;
354 
355 	icr = i2c_smbus_read_byte_data(client, ISL1208_REG_INT);
356 	if (icr < 0) {
357 		dev_err(&client->dev, "%s: reading INT failed\n", __func__);
358 		return icr;
359 	}
360 	alarm->enabled = !!(icr & ISL1208_REG_INT_ALME);
361 
362 	return 0;
363 }
364 
365 static int
366 isl1208_i2c_set_alarm(struct i2c_client *client, struct rtc_wkalrm *alarm)
367 {
368 	struct rtc_time *alarm_tm = &alarm->time;
369 	u8 regs[ISL1208_ALARM_SECTION_LEN] = { 0, };
370 	const int offs = ISL1208_REG_SCA;
371 	struct rtc_time rtc_tm;
372 	int err, enable;
373 
374 	err = isl1208_i2c_read_time(client, &rtc_tm);
375 	if (err)
376 		return err;
377 
378 	/* If the alarm time is before the current time disable the alarm */
379 	if (!alarm->enabled || rtc_tm_sub(alarm_tm, &rtc_tm) <= 0)
380 		enable = 0x00;
381 	else
382 		enable = 0x80;
383 
384 	/* Program the alarm and enable it for each setting */
385 	regs[ISL1208_REG_SCA - offs] = bin2bcd(alarm_tm->tm_sec) | enable;
386 	regs[ISL1208_REG_MNA - offs] = bin2bcd(alarm_tm->tm_min) | enable;
387 	regs[ISL1208_REG_HRA - offs] = bin2bcd(alarm_tm->tm_hour) |
388 		ISL1208_REG_HR_MIL | enable;
389 
390 	regs[ISL1208_REG_DTA - offs] = bin2bcd(alarm_tm->tm_mday) | enable;
391 	regs[ISL1208_REG_MOA - offs] = bin2bcd(alarm_tm->tm_mon + 1) | enable;
392 	regs[ISL1208_REG_DWA - offs] = bin2bcd(alarm_tm->tm_wday & 7) | enable;
393 
394 	/* write ALARM registers */
395 	err = isl1208_i2c_set_regs(client, offs, regs,
396 				  ISL1208_ALARM_SECTION_LEN);
397 	if (err < 0) {
398 		dev_err(&client->dev, "%s: writing ALARM section failed\n",
399 			__func__);
400 		return err;
401 	}
402 
403 	err = isl1208_rtc_toggle_alarm(client, enable);
404 	if (err)
405 		return err;
406 
407 	return 0;
408 }
409 
410 static int
411 isl1208_rtc_read_time(struct device *dev, struct rtc_time *tm)
412 {
413 	return isl1208_i2c_read_time(to_i2c_client(dev), tm);
414 }
415 
416 static int
417 isl1208_i2c_set_time(struct i2c_client *client, struct rtc_time const *tm)
418 {
419 	int sr;
420 	u8 regs[ISL1208_RTC_SECTION_LEN] = { 0, };
421 
422 	/* The clock has an 8 bit wide bcd-coded register (they never learn)
423 	 * for the year. tm_year is an offset from 1900 and we are interested
424 	 * in the 2000-2099 range, so any value less than 100 is invalid.
425 	 */
426 	if (tm->tm_year < 100)
427 		return -EINVAL;
428 
429 	regs[ISL1208_REG_SC] = bin2bcd(tm->tm_sec);
430 	regs[ISL1208_REG_MN] = bin2bcd(tm->tm_min);
431 	regs[ISL1208_REG_HR] = bin2bcd(tm->tm_hour) | ISL1208_REG_HR_MIL;
432 
433 	regs[ISL1208_REG_DT] = bin2bcd(tm->tm_mday);
434 	regs[ISL1208_REG_MO] = bin2bcd(tm->tm_mon + 1);
435 	regs[ISL1208_REG_YR] = bin2bcd(tm->tm_year - 100);
436 
437 	regs[ISL1208_REG_DW] = bin2bcd(tm->tm_wday & 7);
438 
439 	sr = isl1208_i2c_get_sr(client);
440 	if (sr < 0) {
441 		dev_err(&client->dev, "%s: reading SR failed\n", __func__);
442 		return sr;
443 	}
444 
445 	/* set WRTC */
446 	sr = i2c_smbus_write_byte_data(client, ISL1208_REG_SR,
447 				       sr | ISL1208_REG_SR_WRTC);
448 	if (sr < 0) {
449 		dev_err(&client->dev, "%s: writing SR failed\n", __func__);
450 		return sr;
451 	}
452 
453 	/* write RTC registers */
454 	sr = isl1208_i2c_set_regs(client, 0, regs, ISL1208_RTC_SECTION_LEN);
455 	if (sr < 0) {
456 		dev_err(&client->dev, "%s: writing RTC section failed\n",
457 			__func__);
458 		return sr;
459 	}
460 
461 	/* clear WRTC again */
462 	sr = i2c_smbus_write_byte_data(client, ISL1208_REG_SR,
463 				       sr & ~ISL1208_REG_SR_WRTC);
464 	if (sr < 0) {
465 		dev_err(&client->dev, "%s: writing SR failed\n", __func__);
466 		return sr;
467 	}
468 
469 	return 0;
470 }
471 
472 
473 static int
474 isl1208_rtc_set_time(struct device *dev, struct rtc_time *tm)
475 {
476 	return isl1208_i2c_set_time(to_i2c_client(dev), tm);
477 }
478 
479 static int
480 isl1208_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
481 {
482 	return isl1208_i2c_read_alarm(to_i2c_client(dev), alarm);
483 }
484 
485 static int
486 isl1208_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
487 {
488 	return isl1208_i2c_set_alarm(to_i2c_client(dev), alarm);
489 }
490 
491 static irqreturn_t
492 isl1208_rtc_interrupt(int irq, void *data)
493 {
494 	unsigned long timeout = jiffies + msecs_to_jiffies(1000);
495 	struct i2c_client *client = data;
496 	struct rtc_device *rtc = i2c_get_clientdata(client);
497 	int handled = 0, sr, err;
498 
499 	/*
500 	 * I2C reads get NAK'ed if we read straight away after an interrupt?
501 	 * Using a mdelay/msleep didn't seem to help either, so we work around
502 	 * this by continually trying to read the register for a short time.
503 	 */
504 	while (1) {
505 		sr = isl1208_i2c_get_sr(client);
506 		if (sr >= 0)
507 			break;
508 
509 		if (time_after(jiffies, timeout)) {
510 			dev_err(&client->dev, "%s: reading SR failed\n",
511 				__func__);
512 			return sr;
513 		}
514 	}
515 
516 	if (sr & ISL1208_REG_SR_ALM) {
517 		dev_dbg(&client->dev, "alarm!\n");
518 
519 		rtc_update_irq(rtc, 1, RTC_IRQF | RTC_AF);
520 
521 		/* Clear the alarm */
522 		sr &= ~ISL1208_REG_SR_ALM;
523 		sr = i2c_smbus_write_byte_data(client, ISL1208_REG_SR, sr);
524 		if (sr < 0)
525 			dev_err(&client->dev, "%s: writing SR failed\n",
526 				__func__);
527 		else
528 			handled = 1;
529 
530 		/* Disable the alarm */
531 		err = isl1208_rtc_toggle_alarm(client, 0);
532 		if (err)
533 			return err;
534 	}
535 
536 	return handled ? IRQ_HANDLED : IRQ_NONE;
537 }
538 
539 static const struct rtc_class_ops isl1208_rtc_ops = {
540 	.proc = isl1208_rtc_proc,
541 	.read_time = isl1208_rtc_read_time,
542 	.set_time = isl1208_rtc_set_time,
543 	.read_alarm = isl1208_rtc_read_alarm,
544 	.set_alarm = isl1208_rtc_set_alarm,
545 };
546 
547 /* sysfs interface */
548 
549 static ssize_t
550 isl1208_sysfs_show_atrim(struct device *dev,
551 			 struct device_attribute *attr, char *buf)
552 {
553 	int atr = isl1208_i2c_get_atr(to_i2c_client(dev));
554 	if (atr < 0)
555 		return atr;
556 
557 	return sprintf(buf, "%d.%.2d pF\n", atr >> 2, (atr & 0x3) * 25);
558 }
559 
560 static DEVICE_ATTR(atrim, S_IRUGO, isl1208_sysfs_show_atrim, NULL);
561 
562 static ssize_t
563 isl1208_sysfs_show_dtrim(struct device *dev,
564 			 struct device_attribute *attr, char *buf)
565 {
566 	int dtr = isl1208_i2c_get_dtr(to_i2c_client(dev));
567 	if (dtr < 0)
568 		return dtr;
569 
570 	return sprintf(buf, "%d ppm\n", dtr);
571 }
572 
573 static DEVICE_ATTR(dtrim, S_IRUGO, isl1208_sysfs_show_dtrim, NULL);
574 
575 static ssize_t
576 isl1208_sysfs_show_usr(struct device *dev,
577 		       struct device_attribute *attr, char *buf)
578 {
579 	int usr = isl1208_i2c_get_usr(to_i2c_client(dev));
580 	if (usr < 0)
581 		return usr;
582 
583 	return sprintf(buf, "0x%.4x\n", usr);
584 }
585 
586 static ssize_t
587 isl1208_sysfs_store_usr(struct device *dev,
588 			struct device_attribute *attr,
589 			const char *buf, size_t count)
590 {
591 	int usr = -1;
592 
593 	if (buf[0] == '0' && (buf[1] == 'x' || buf[1] == 'X')) {
594 		if (sscanf(buf, "%x", &usr) != 1)
595 			return -EINVAL;
596 	} else {
597 		if (sscanf(buf, "%d", &usr) != 1)
598 			return -EINVAL;
599 	}
600 
601 	if (usr < 0 || usr > 0xffff)
602 		return -EINVAL;
603 
604 	return isl1208_i2c_set_usr(to_i2c_client(dev), usr) ? -EIO : count;
605 }
606 
607 static DEVICE_ATTR(usr, S_IRUGO | S_IWUSR, isl1208_sysfs_show_usr,
608 		   isl1208_sysfs_store_usr);
609 
610 static struct attribute *isl1208_rtc_attrs[] = {
611 	&dev_attr_atrim.attr,
612 	&dev_attr_dtrim.attr,
613 	&dev_attr_usr.attr,
614 	NULL
615 };
616 
617 static const struct attribute_group isl1208_rtc_sysfs_files = {
618 	.attrs	= isl1208_rtc_attrs,
619 };
620 
621 static int
622 isl1208_probe(struct i2c_client *client, const struct i2c_device_id *id)
623 {
624 	int rc = 0;
625 	struct rtc_device *rtc;
626 
627 	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
628 		return -ENODEV;
629 
630 	if (isl1208_i2c_validate_client(client) < 0)
631 		return -ENODEV;
632 
633 	if (client->irq > 0) {
634 		rc = devm_request_threaded_irq(&client->dev, client->irq, NULL,
635 					       isl1208_rtc_interrupt,
636 					       IRQF_SHARED | IRQF_ONESHOT,
637 					       isl1208_driver.driver.name,
638 					       client);
639 		if (!rc) {
640 			device_init_wakeup(&client->dev, 1);
641 			enable_irq_wake(client->irq);
642 		} else {
643 			dev_err(&client->dev,
644 				"Unable to request irq %d, no alarm support\n",
645 				client->irq);
646 			client->irq = 0;
647 		}
648 	}
649 
650 	rtc = devm_rtc_device_register(&client->dev, isl1208_driver.driver.name,
651 				  &isl1208_rtc_ops,
652 				  THIS_MODULE);
653 	if (IS_ERR(rtc))
654 		return PTR_ERR(rtc);
655 
656 	i2c_set_clientdata(client, rtc);
657 
658 	rc = isl1208_i2c_get_sr(client);
659 	if (rc < 0) {
660 		dev_err(&client->dev, "reading status failed\n");
661 		return rc;
662 	}
663 
664 	if (rc & ISL1208_REG_SR_RTCF)
665 		dev_warn(&client->dev, "rtc power failure detected, "
666 			 "please set clock.\n");
667 
668 	rc = sysfs_create_group(&client->dev.kobj, &isl1208_rtc_sysfs_files);
669 	if (rc)
670 		return rc;
671 
672 	return 0;
673 }
674 
675 static int
676 isl1208_remove(struct i2c_client *client)
677 {
678 	sysfs_remove_group(&client->dev.kobj, &isl1208_rtc_sysfs_files);
679 
680 	return 0;
681 }
682 
683 static const struct i2c_device_id isl1208_id[] = {
684 	{ "isl1208", 0 },
685 	{ "isl1218", 0 },
686 	{ }
687 };
688 MODULE_DEVICE_TABLE(i2c, isl1208_id);
689 
690 static const struct of_device_id isl1208_of_match[] = {
691 	{ .compatible = "isil,isl1208" },
692 	{ .compatible = "isil,isl1218" },
693 	{ }
694 };
695 MODULE_DEVICE_TABLE(of, isl1208_of_match);
696 
697 static struct i2c_driver isl1208_driver = {
698 	.driver = {
699 		.name = "rtc-isl1208",
700 		.of_match_table = of_match_ptr(isl1208_of_match),
701 	},
702 	.probe = isl1208_probe,
703 	.remove = isl1208_remove,
704 	.id_table = isl1208_id,
705 };
706 
707 module_i2c_driver(isl1208_driver);
708 
709 MODULE_AUTHOR("Herbert Valerio Riedel <hvr@gnu.org>");
710 MODULE_DESCRIPTION("Intersil ISL1208 RTC driver");
711 MODULE_LICENSE("GPL");
712